The present invention is generally directed to material handling vehicles and, more particularly, to a vehicle having a vertically floating drive assembly.
Automatic guided vehicles (AGVs) are used throughout the material handling industry to transport loads. The term AGV is commonly used to refer to robust vehicle designs having any of a number of available automated guidance systems. Automatic guided carts (AGCs) is a term commonly used to refer to a less robust vehicle used for similar but smaller-scale applications. Current AGC designs generally include a frame with swivel castors located at the four corners of the frame. Other features may include a drive wheel assembly and rigid castors for directional control of the cart. In one current design, two rigid castors are fixed to the frame and located approximately midway between the swivel castors on each side of the cart frame. The two pair of swivel castor axes and the rigid castor axis are generally parallel to each other. The steerable driving unit is attached to the cart frame, generally by way of a plate that is hinged and spring loaded from the cart frame to ensure that the steerable drive wheel maintains adequate traction with the support surface.
While this arrangement is generally acceptable for uniform support surfaces, situations where the floor is not level and flat may give rise to losses in the directional control of the cart. More particularly, when the cart encounters an uneven surface, the direct mounting of the swivel and rigid castors to the cart frame may cause one or more of the three sets of castors to become disengaged from the support surface. Since the rigid castors are used for direction control of the cart, loss of contact between the rigid castors and the floor may cause loss of directional control of the cart. The only wheel that has significantly uniform contact with the floor is the hinged and spring loaded steerable drive wheel.